Originally posted by Hawco
Do aircraft have a certain shelf life?
Yes they do....usually. You have corrosion and fatigue of the airplane. Planes bend and sooner or later fatigue takes it's toll and you have to start replacing big expensive parts. However, some planes can last almost indefinently if they're willing to put money into them. Look at the B-52 for instance. But the older they are the more expensive to rebuild and the harder it is to get parts. On the other hand, lots of the newest planes will never last as long as the Tomcat because there is much more extensive use of composite materials and it's much harder to completely rebuild a composite part than it is to, say, fabricate a new wing spar out of metal.
Originally posted by Hawco
How long does it take to actually make these things?
Well, it sort of depends on what you mean. If you're asking how long it would take to develop a new plane and get it flying you're talking years, even longer to get it flying operationally. I saw both the F-22 and F-23 prototypes when they were still "black" programs and that was in 1985 or 86. I first saw them fly in 1987. The F-22 just went operational last year. If you're talking about how long an existing production line takes to build a single plane like an F-14 you'd be talking anywhere from a few months to a year, depending on the production schedule and how many are needed.
Originally posted by Hawco
What sort of factors decide when it's time to change planes and get another one?
The top three factors are money, money and money. Just kidding...sorta. It was simpler in the past when airplanes were just mechanical devices. Their performance was based simply on their physical construction so, in order to get a significant improvement you needed a whole new plane. Nowadays, airplanes are as much their weapon system as their airframe. Lots of older airframes are updated with new systems that give them far more capability than was dreamed of when they were first built. Again, the B-52 is a prime example. The F-14 was originally built as primarily an interceptor for fleet defense but, with system and engine upgrades it eventually became the Navy's best bomber in Afghanistan and Iraq. As far as when does it make more sense to build a new airplane vice rebuilding and updating old ones? Well, the Navy has wrestled with that problem for years. They invested far too much into the "Super" Hornet when the same money could have been used to build brand new Tomcats with better range, speed and payload. On the other hand, when they decided they really did need a stealth airplane neither the Hornet or Tomcat would ever fit that bill so we have the F-35 coming.
Originally posted by Hawco
What about computer parts ? How can they put the latest and greatest computers in these things when hardware is constantly changing??
Now that is a great question but hardware changes at a much slower rate than computers. It's hard to believe but the Commodore 64 had more computing power than the F-14A but even that tiny computer gave the airplane tremendous power for its time. The F-14D had well over a 1,000 times the computing power of the F-14A. More than hardware, it was actually the improved computers, digitial buses, and software that gave the D much more capability than the A. Lots don't realize it but the development time for military hardware virtually guarantees that their computers will already be outdated (to the point of being unable to get parts) before the hardware is even deployed for the first time. The military is doing lots to try to fix this but it takes time to develop a weapon and computers are improving at incredible rates so it's just the nature of the beast.
